Homebrew PCBs

Sitting here looking at my etched boards with the toner still on them, 
I got to thinking that I could leave it there.  Use a Q-tip to remove 
the toner from the solder pads and leave the rest there.  This might 
help to reduce oxidization of the copper? 

I suppose there could be a problem with the toner melting and flowing 
back into solder joints as you add components though.  

Just an idea, curious if anyone has tried this and if they had any 
success.

Chris

I've soldered right through the toner on pads on th boards. The problem 
with acetone is the toner melts and spreads around and you get a messy 
looking board.

  All in all I've found it not really worth it, just clean the whole board 
right before you solder. Oxidation has not been a problem. If you really 
care about long term, use a conformal coating when the boards been completed.

-carl


At 02:52 PM 10/25/2005, you wrote:

>Sitting here looking at my etched boards with the toner still on them,
>I got to thinking that I could leave it there.  Use a Q-tip to remove
>the toner from the solder pads and leave the rest there.  This might
>help to reduce oxidization of the copper?
>
>I suppose there could be a problem with the toner melting and flowing
>back into solder joints as you add components though.
>
>Just an idea, curious if anyone has tried this and if they had any
>success.
>
>Chris
>

On Tue, 25 Oct 2005 20:52:49 +0200, lcdpublishing  
<lcdpublishing@...> wrote:

> Sitting here looking at my etched boards with the toner still on them,
> I got to thinking that I could leave it there.  Use a Q-tip to remove
> the toner from the solder pads and leave the rest there.  This might
> help to reduce oxidization of the copper?
> I suppose there could be a problem with the toner melting and flowing
> back into solder joints as you add components though.
> Just an idea, curious if anyone has tried this and if they had any
> success.
> Chris


I would be afraid of acid residue trapped/caught by the toner.
After etching and rinsing i scrape the toner off with a steel scraper,  
much less messy than acetone. I wipe off the last remains with that, if  
there are any.

Then i coat it with a mixture of colophony resin and alcohol, which  
prevents oxidation and acts as a flux.

ST

Okay, that's a new one for me...  Colophony Resin? 

What is that stuff and where can you get it? I am willing to give 
just about anything a try - this if fun....

Till, see my newest post about fixing traces :-(

Chris






--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan" 
<stefan_trethan@g...> wrote:
>
> On Tue, 25 Oct 2005 20:52:49 +0200, lcdpublishing  
> <lcdpublishing@y...> wrote:
> 
> > Sitting here looking at my etched boards with the toner still on 
them,
> > I got to thinking that I could leave it there.  Use a Q-tip to 
remove
> > the toner from the solder pads and leave the rest there.  This 
might
> > help to reduce oxidization of the copper?
> > I suppose there could be a problem with the toner melting and 
flowing
> > back into solder joints as you add components though.
> > Just an idea, curious if anyone has tried this and if they had 
any
> > success.
> > Chris
> 
> 
> I would be afraid of acid residue trapped/caught by the toner.
> After etching and rinsing i scrape the toner off with a steel 
scraper,  
> much less messy than acetone. I wipe off the last remains with 
that, if  
> there are any.
> 
> Then i coat it with a mixture of colophony resin and alcohol, 
which  

> prevents oxidation and acts as a flux.
> 
> ST
>

On Tue, 25 Oct 2005 22:42:12 +0200, lcdpublishing  
<lcdpublishing@...> wrote:

> Okay, that's a new one for me...  Colophony Resin?
> What is that stuff and where can you get it? I am willing to give
> just about anything a try - this if fun....
> Till, see my newest post about fixing traces
> Chris


It's resin, from trees like pine, with the turpentine removed.

<http://en.wikipedia.org/wiki/Colophony>

It's widely used as soldering flux, and can be left on the PCB especially  
if there are no special requirements for extreme isolation resistance  
etc.. It is not active (not etching the copper) when cold.

If you get chunks of it you can solve it in alcohol and paint it on, or  
you can buy spraycans where it's already mixed.

It is important to note that there are wide color/quality variations, from  
almost black to almost like glass. If it is used as flux and should remain  
on the PCB the light colored qualities are preferrable.

It's also useful as a general purpose brush-on flux.

ST

Oh, it's Rosin!  That is interesting. I will have to find some and 
give it a try.  Being a natural product, I suspect it shouldn't be 
too hard to find (and have shipped).

Thanks!

Chris



--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan" 
<stefan_trethan@g...> wrote:
>
> On Tue, 25 Oct 2005 22:42:12 +0200, lcdpublishing  
> <lcdpublishing@y...> wrote:
> 
> > Okay, that's a new one for me...  Colophony Resin?
> > What is that stuff and where can you get it? I am willing to give
> > just about anything a try - this if fun....
> > Till, see my newest post about fixing traces
> > Chris
> 
> 
> It's resin, from trees like pine, with the turpentine removed.
> 
> <http://en.wikipedia.org/wiki/Colophony>
> 
> It's widely used as soldering flux, and can be left on the PCB 
especially  
> if there are no special requirements for extreme isolation 
resistance  
> etc.. It is not active (not etching the copper) when cold.
> 
> If you get chunks of it you can solve it in alcohol and paint it 
on, or  
> you can buy spraycans where it's already mixed.
> 
> It is important to note that there are wide color/quality 
variations, from  
> almost black to almost like glass. If it is used as flux and 
should remain  

> on the PCB the light colored qualities are preferrable.
> 
> It's also useful as a general purpose brush-on flux.
> 
> ST
>

lcdpublishing wrote:

>Oh, it's Rosin!  That is interesting. I will have to find some and 
>give it a try.  Being a natural product, I suspect it shouldn't be 
>too hard to find (and have shipped).
>
>Thanks!
>
>Chris
>
>
>  
>
Try a music store for the rosin cake they use for violin bows - or a 
sporting goods store for the rosin in baseball pitchers bags or weight 
lifters and gymnasts hand grips - just possibilities.  The solid should 
dissolve in rubbing alchohol  for application.

Norm

On Wed, 26 Oct 2005 04:01:17 +0200, Norm Stewart <normstewart@...>  
wrote:

>
> Try a music store for the rosin cake they use for violin bows - or a
> sporting goods store for the rosin in baseball pitchers bags or weight
> lifters and gymnasts hand grips - just possibilities.  The solid should
> dissolve in rubbing alchohol  for application.
> Norm


yes, though i've heard the violin stuff may contain additives and is  
outrageously expensive.
You can also find it at good arts/paints stores, and your chemicals store.

I got my "chunks" from an electronics mail order, but they were expensive  
and bad quality (dark). The spray i got from another mailorder, and it's a  
lighter quality. The only bad thing is that it can stay slightly tacky.


There was also discussion here about a spray paint (transparent green)  
that can be applied and "soldered through" leaving a soldermask-like  
appearance. Look in the archives.


ST

I remember that discussion but perhaps I didn't read it through.  I 
even remember asking about how to mask off the pads to prevent the 
paint from getting on them - don't recall getting an answer.  
Perhaps it is because you can solder right through it!  

I may have to give that a try too.



 
> There was also discussion here about a spray paint (transparent 
green)  
> that can be applied and "soldered through" leaving a soldermask-
like  

> appearance. Look in the archives.
> 
> 
> ST
>

On Wed, 26 Oct 2005 13:17:21 +0200, lcdpublishing  
<lcdpublishing@...> wrote:

> I remember that discussion but perhaps I didn't read it through.  I
> even remember asking about how to mask off the pads to prevent the
> paint from getting on them - don't recall getting an answer.
> Perhaps it is because you can solder right through it!
> I may have to give that a try too.


Well, there are such stickers in the right shape. You could probably punch  
your own...

If it can be soldered through it is surely not acting as a flux, and i  
don't want to speculate about the fumes.

ST

Someone mentioned petroleum grease dabbed onto the pads. You could
also put dabs of latex on them, it isn't messy and rolls off once it's
dry.

It's sometimes used in plastic model painting as a paint mask. Don't
pay $10 for a tiny bottle, though. There are other sources, at one
time you could get largeish bottles of latex at the hardware store in
the carpet department. I think it was a product for painting on the
bottom of rugs to prevent them from slipping.

And of course casting and prosthetic supplies. I just got a gallon
from GetSPFX.com for $35 plus shipping. RD-407

Steve Greenfield

--- In Homebrew_PCBs@yahoogroups.com, "lcdpublishing"
<lcdpublishing@y...> wrote:

>
> I remember that discussion but perhaps I didn't read it through.  I 
> even remember asking about how to mask off the pads to prevent the 
> paint from getting on them - don't recall getting an answer.  
> Perhaps it is because you can solder right through it!  
> 
> I may have to give that a try too.
> 
>  
> > There was also discussion here about a spray paint (transparent 
> green)  
> > that can be applied and "soldered through" leaving a soldermask-
> like  
> > appearance. Look in the archives.
> > 
> > 
> > ST
> >
>